"Both sides of supporters will be used to the British way of policing, but they need to be respectful of how policing is done there," said the former Special Branch counter-terrorist detective, who is now an expert on crime and security at Liverpool John Moores University," he said.

"There will be spotters from the British football intelligence unit looking for known individuals and trouble-makers who have injunctions out against them.

"There will always be one or two idiots who will have been drinking all day and are looking for trouble and they will be identified quite rightly and eliminated," he added.

Six England fans were jailed following violence in Marseille at the weekend while French police said 150 "well-trained" Russian hooligans were behind the trouble at the end of the match at the Stade Velodrome.

But for those who go with or without tickets, Dr Lowe said UK officers would be advocating a "softly-softly" approach as riot gear and tear gas would be a shock for most supporters.

"Our officers tend to build up a rapport with supporters and are more used to the banter," he added.

Ian Whitfield, a former public order commander with Merseyside police who has policed Premier League, European and international football matches, said: "It's going to be a difficult situation because the French police have a fundamentally very different approach and don't have a model of active engagement with the fans.

"Our officers can't dictate operational policing, they can only advise, but on the ground they will be chatting to supporters and known offenders before the game and gauging the mood.

"They will also be getting the message across about keeping a low profile which can help the supporters to self-police when people are causing trouble."

Mr Whitfield is also a senior lecturer at the Liverpool Centre for Advanced Policing Studies and has a specialism in researching crowd behaviour.

Gerry Toms, a former chief superintendant with South Wales Police, and ex-general manager of Cardiff's Millennium Stadium, said there was very little historical evidence of problems between Welsh and English supporters and most of the interaction around the match would be "friendly banter".

He said: "The UK football intelligence system is one of the best in Europe and where the English and Welsh officers will be helping is by advising that if French officers are not comfortable with fans' behaviour, early intervention and talking to supporters works best.

Tear gas

"They will be gauging the mood and trying to see that boisterous singing isn't read as a threat so the French police don't make an inappropriate or heavy-handed response.

"The problem is if the French riot police use tear gas indiscriminately as happened in Marseille, you create the opposite effect.

"You don't want a riot with everybody against police - that breaks troublemakers up into smaller groups which makes the problem spread wider."

He said there are fears Russian fans will try to get from their next match in nearby Lille to cause trouble with English fans.

"Lens is a very small place and these people work best under cover of a large crowd so I don't think it will be as effective.

"The ban on alcohol in bars will also help those who could be caught up in violence from drinking too much and the French police will be listening to the English police and saying to supporters: 'This is an historic occasion with two UK teams playing in an international tournament - enjoy the occasion and don't antagonise each other."